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The factors that control the spatial tuning of hippocampal neurons are incompletely understood, and there is no generally agreed upon definition of what constitutes a "place field". One factor that must be considered is the phenomenon of "phase precession". As a rat passes through the place field of a particular hippocampal neuron, its spikes shift to(More)
Although hippocampal interneurons typically do not show discrete regions of elevated firing in an environment, such as seen in pyramidal cell place fields, they do exhibit significant spatial modulation (McNaughton et al., 1983a). Strong monosynaptic coupling between pyramidal neurons and nearby interneurons in the CA1 stratum pyramidale has been strongly(More)
The medial prefrontal cortex (mPFC) plays a critical role in the organization of goal-directed behaviors and in the learning of reinforcement contingencies. Given these observations, it was hypothesized that mPFC neurons may store associations between sequentially paired stimuli when both stimuli contribute to the prediction of reward. To test this(More)
Memory trace reactivation in hippocampal ensembles during sleep has been suggested as a coordinating mechanism for consolidation of new memories. Here we propose a simple statistical scheme allowing analysis of the reactivation of firing rate modulations, with a well-defined null hypothesis. This method allowed reliable detection of ensemble reactivation(More)
Goal-directed behaviors require the consideration and expenditure of physical effort. The anterior cingulate cortex (ACC) appears to play an important role in evaluating effort and reward and in organizing goal-directed actions. Despite agreement regarding the involvement of the ACC in these processes, the way in which effort-, reward-, and motor-related(More)
The physical effort required to seek out and extract a resource is an important consideration for a foraging animal. A second consideration is the variability or risk associated with resource delivery. An intriguing observation from ethological studies is that animals shift their preference from stable to variable food sources under conditions of increased(More)
Self-motion information influences spatially-specific firing patterns exhibited by hippocampal neurons. Moreover, these firing patterns can repeat across similar subsegments of an environment, provided that there is similarity of path shape and head orientations across subsegments. The influence of self-motion variables on repeating fields remains to be(More)
UNLABELLED Spatial and episodic memory performance declines with age, and the neural basis for this decline is not well understood. Sharp-wave ripples are brief (∼70 ms) high-frequency oscillatory events generated in the hippocampus and are associated with the consolidation of spatial memories. Given the connection between ripple oscillations and memory(More)
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